DirectoryQ (Built-in Mathematica Symbol)

DirectoryQ["name"] gives True if the directory with the specified name exists, and gives False otherwise.

DivideBy (Built-in Mathematica Symbol)

x /= c divides x by c and returns the new value of x.

Evaluator (Built-in Mathematica Symbol)

Evaluator is an option for objects such as Button, Dynamic, and Cell that gives the name of the kernel to use to evaluate their contents.

FactorialPower (Built-in Mathematica Symbol)

FactorialPower[x, n] gives the factorial power x (n). FactorialPower[x, n, h] gives the step-h factorial power x (n, h).

First (Built-in Mathematica Symbol)

First[expr] gives the first element in expr.

FunctionSpace (Built-in Mathematica Symbol)

FunctionSpace is an option for FindSequenceFunction and related functions that specifies the space of functions to consider for representations.

GapPenalty (Built-in Mathematica Symbol)

GapPenalty is an option for SequenceAlignment and related functions that gives the additional cost associated with each gap corresponding to a run of insertions or deletions.

GenerateConditions (Built-in Mathematica Symbol)

GenerateConditions is an option for Integrate, Sum, and similar functions that specifies whether explicit conditions on parameters should be generated in the result.

Head (Built-in Mathematica Symbol)

Head[expr] gives the head of expr.

IgnoreCase (Built-in Mathematica Symbol)

IgnoreCase is an option for string manipulation and searching functions that specifies whether lowercase and uppercase letters should be treated as equivalent.